1. Technical Field
This invention relates to the field of telephony and, more particularly, to providing telephony services to subscribers.
2. Description of the Related Art
The delivery of most telephony services and features are tied to the directory number of a calling party or a called party. In fact, nearly all of the activities performed by a conventional telephony system, whether the public switched telephone network (PSTN) or an Internet protocol (IP) telephony system, are based on such directory numbers. The dialed directory number can be referred to as the DNIS in reference to directory number identification service, a service which identifies for a receiving party the number dialed by a calling party. The directory number of the calling party can be referred to as an ANI in reference to automatic number identification, the service which provides the receiving party with the directory number of the calling party.
For example, when a calling party initiates a call to a receiving party, the DNIS and the ANI can be used to authenticate the call. Authentication can include tasks such as finding the ANI in a list of authorized subscribers and ensuring that the DNIS is valid. Taking another example, the switching of calls to and from a subscriber also can be achieved through the use of the subscriber's directory number. That is, if a calling party places a call to a receiving party, the call can be routed to the receiving party based on an area code and/or an exchange code of the DNIS.
The reliance of conventional telephony systems on the DNIS and ANI not only determines how features and services are to be implemented and delivered, but also can dictate the mode of operation of other major portions of the telephony system. In illustration, telephony billing systems are largely based upon the directory number of a subscriber. Given the mobile nature of today's society, however, billing subscribers according to their directory number may not be the most efficient billing method available. For example, as a subscriber moves from one location to another, the subscriber may utilize telephony equipment associated with a directory number that is different from that of the “mobile” subscriber. Yet conventional telephony systems continue to link the delivery of telephony services with directory numbers.